An electric motor with a stator winding interconnection comprising several ring conductors is known from DE 10 2004 050374 A1. The electric motor is configured as an inner rotor motor. The stator of the electric motor is a conventional slotted stator, consisting of a hollow-cylindrical iron core with several radially projecting teeth onto which the individual coils of the stator winding are wound. The stator is surrounded by a hollow-cylindrical housing into which the ring conductors of the stator winding interconnection, too, are inserted. The ring conductors are punched from copper sheet and each have an axially bent terminal lug for the external electrical contact. All ring conductors are arranged at a front end of the stator winding and inserted into the hollow-cylindrical housing of the electric motor. Various recesses, respectively, steps are formed in the inner wall of the housing which serve as stop for the ring conductors. The steps of the inner wall of the housing make sure that the ring conductors are held axially spaced apart from each other in the housing. Each winding wire end of the stator winding is soldered to one of the ring conductors.
The stator winding interconnection described in DE 10 2004 050374 A1 requires a specific configuration of the electric motor housing, thus necessitating a complicated manufacture of the housing. In addition, the motor cannot be set up without this specifically configured housing. To ensure that the individual ring conductors are sufficiently electrically insulated from each other a certain minimum distance plus a safety margin has to be provided between the axially, successively arranged ring conductors. Hence, the electric motor described in DE 10 2004 050374 A1 is relatively long in the axial direction.
DE 10 2011 100863 A1 and DE 10 2011 100843 A1 each disclose an electric motor having a stator winding interconnection which comprises several so-called rail parts configured in the form of annulus sections. Similar to the ring conductors according to DE 10 2004 050374 A1 the rail parts configured in the form of annulus sections are arranged to be axially spaced apart from each other at a front end of the stator winding and are each in electrical contact with a winding wire end of the stator winding. Each of the rail parts configured in the form of annulus sections comprises an axially projecting lug which serves for the external electrical contact. The rail parts are not only spaced apart from each other in the axial direction, but are also offset from each other in the circumferential direction. The stator winding and the rail parts arranged at the front end of the stator winding are encapsulated by an electrically insulating encapsulating material, while the axially bent lugs of the rail parts configured in the form of annulus sections project from the encapsulating material.
The manufacture of the electric motor described in DE 10 2011 100863 A1 and DE 10 2011 100843 A1 is relatively complicated as the rail parts configured in the form of annulus sections have to be spaced apart from each other with exact distances there between prior to encapsulating them, together with the stator winding, by the electrically insulating encapsulating material.